1. Field of the Invention
This invention relates to an image reading system having a document feeding device for automatically feeding one or more documents to an image reading position, and more particularly to the document feeding device of the image reading system, which enables card-like documents such as a name card to be accurately set at a delivery standard point and securely forwarded to the image reading position.
2. Description of the Prior Art
An optical image reading device such as an image scanner and card reader, which has been used for reading characters, images or the like printed on a document in the form of electronic information data, are often provided with a document feeder for automatically feeding the document to the document reading device.
Japanese Patent Application Public Disclosure HEI 3-235470(A) and Japanese Utility Model Application Public Disclosure HEI 1-108659(A) each disclose an image reading device for reading an image on a document such as a name card and an envelope. In this image reading device, the image on the document is read when the document being forwarded along a document setting face of the device toward an image reading position by driving document feeding rollers passes through the image reading position.
Although a copying machine or facsimile which is a kind of image reading device may be provided with an ordinary automatic document feeder, the document feeder applied to an image scanner or a card reader necessitates high performance to reliably forward the documents one by one to the image reading position. Besides, the document to be fed to the image scanner or card reader must be set on the document feeder so as to accurately place the leading end of the document in position at the delivery standard point determined on the document feeder. Inaccuracy in positioning the document will entail decrease in accuracy of optical character recognition (OCR) or other image reading performance.
It is convenient to use a demountable document feeder capable of being easily attached to or detached from a stand-alone type card reader to which documents to be subjected to image reading must be inserted one by one. The demountable document feeder which is united with the card reader is further required to acquire motive power from the card reader to feed the document to the card reader, and be controlled on the side of the card reader, so that the entire system including the document feeder can be managed collectively in cooperation with the card reader.